Population Decline

Recruitment is essential for the maintenance of populations, but far more is typically known about the more easily-observed adult stages than their smaller, often microscopic early life-history counterparts. This discrepancy can be particularly problematic for populations of foundation species that create biogenic habitat for a multitude of other taxa, but are themselves prime candidates for exploitation, fragmentation, and loss, and therefore become the focus of restoration eVorts partly or fully dependent on recruitment. The purpose of this study was to improve ecological understanding for early life-history stages of the habitat-forming marine alga Cystoseira barbata (Stackhouse) C. Agardh (Fucales: Sargassaceae), member of a genus that has experienced considerable fragmentation and population decline on European coasts. Using experimental manipulations of water temperature, light intensity, and sediment accumulation, we observed that sediment virtually precluded recruitment of C. barbata, and greatly impacted the survival of recently settled germlings (up to »83% mortality). Stronger intensities of light facilitated the growth of germlings, including the capacity for »50% of them to outgrow detrimental sediment and survive. Temperature (10 vs. 16°C) had no eVect on early recruitment, survival, or growth. This information helps to identify likely causes and locations of recruitment failure, and by extension, the conditions needed (either naturally or through human intervention) to facilitate recruitment and possible habitat restoration. Ultimately, this knowledge can increase our capacity to predict population persistence and the likely success of restoration eVorts. Communicated by S. D. Connell.

The loggerhead sea turtle (Caretta caretta) nests on sand beaches, has both oceanic and neritic life stages, and migrates internationally. We analyzed an 18-year time series of Index Nesting Beach Survey (Index) nest-count data to describe spatial and temporal trends in loggerhead nesting on Florida (USA) beaches. The Index data were highly resolved: 368 fixed zones (mean length 0.88 km) were surveyed daily during annual 109-day survey seasons. Spatial and seasonal coverage averaged 69% of estimated total nesting by loggerheads in the state. We carried out trend analyses on both annual survey-region nest-count totals (N ¼ 18) and annual zone-level nest densities (N ¼ 18 3 368 ¼ 6624). In both analyses, negative binomial regression models were used to fit restricted cubic spline curves to aggregated nest counts. Between 1989 and 2006, loggerhead nest counts on Florida Index beaches increased and then declined, with a net decrease over the 18-year period. This pattern was evident in both a trend model of annual survey-region nest-count totals and a mixed-effect, ''single-region'' trend model of annual zone-level nest densities that took into account both spatial and temporal correlation between counts. We also saw this pattern in a zone-level model that allowed trend line shapes to vary between six coastal subregions. Annual mean zone-level nest density declined significantly (À28%; 95% CI: À34% to À21%) between 1989 and 2006 and declined steeply (À43%; 95% CI: À48% to À39%) during 1998-2006. Rates of change in annual mean nest density varied more between coastal subregions during the ''mostly increasing'' period prior to 1998 than during the ''steeply declining'' period after 1998. The excellent fits (observed vs. expected count R 2. 0.91) of the mixed-effect zone-level models confirmed the presence of strong, positive, within-zone autocorrelation (R. 0.93) between annual counts, indicating a remarkable year-to-year consistency in the longshore spatial distribution of nests over the survey region. We argue that the decline in annual loggerhead nest counts in peninsular Florida can best be explained by a decline in the number of adult female loggerheads in the population. Causes of this decline are explored.

Epidermal changes caused by a chytridiomycete fungus (Chytridiomycota; Chytridiales) were found in sick and dead adult anurans collected from montane rain forests in Queensland (Australia) and Panama during mass mortality events associated with significant population declines. We also have found this new disease associated with morbidity and mortality in wild and captive anurans from additional locations in Australia and Central America. This is the first report of parasitism of a vertebrate by a member of the phylum Chytridiomycota. Experimental data support the conclusion that cutaneous chytridiomycosis is a fatal disease of anurans, and we hypothesize that it is the proximate cause of these recent amphibian declines.

The White-tailed Tropicbird Phaethon lepturus breeding population of Aride Island, Seychelles, has experienced a strong decline in the recent past. To predict the future trends of the White-tailed Tropicbird population on Aride Island and understand the urgency of applying management procedures, we developed a population matrix model. We estimated White-tailed Tropicbird adult survival rate over a 12-year period and investigated whether oceanographic conditions (El Niño Southern Oscillation, ENSO, and inter-annual climate variability in the Indian Ocean, Indian Ocean Dipole, IOD) or local factors (Pisonia grandis fruiting events) potentially affect adult survival. Annual adult survival could not be linked to inter-annual variability in oceanographic conditions, but may be more influenced by Pisonia fruiting events, which, overall, accounts for 23.2% of the adult mortality. The growth rate of the population, primarily influenced by annual adult survival, was estimated to be 0.946, which indicates an annual population decline of 5.4%. At the current rate, the probability of extinction of this population would be 99% in 170 years. Management scenarios studied through Monte Carlo simulations, assuming small increments in adult survival and/or breeding success, dramatically reduce the risk of extinction of White-tailed Tropicbirds. Habitat management, in order to maintain an open canopy and little understorey vegetation, appears to be crucial for the conservation of White-tailed Tropicbirds on Aride Island, as has already been shown for other groundnesting tropical seabirds nesting on forested islands.

Little is known about baseline concentrations of adrenal hormones and hormonal responses to stress in sea ducks, although significant population declines documented in several species suggest that sea ducks are exposed to increased levels of environmental stress. Such declines have been observed in geographically distinct harlequin duck populations. We performed an adrenocorticotropic hormone (ACTH) challenge to evaluate adrenal function and characterize corticosterone concentrations in captive harlequin ducks and investigated the effects of capture, surgery, and short term confinement on corticosterone concentrations in wild harlequin ducks. Harlequin ducks responded to the ACTH challenge with an average three-fold increase in serum corticosterone concentration approximately 90 min post injection, and a four-to five-fold increase in fecal glucocorticoid concentration 2 to 4 h post injection. Serum corticosterone concentrations in wild harlequin ducks increased within min of capture and elevated levels were found for several hours post capture, indicating that surgery and confinement maintain elevated corticosterone concentrations in this species. Mean corticosterone concentrations in wild harlequin ducks held in temporary captivity were similar to the maximum response levels during the ACTH challenge in captive birds. However, large variation among individuals was observed in responses of wild birds, and we found additional evidence suggesting that corticosterone responses varied between hatch year and after hatch year birds.

Population declines due to chytridiomycosis among frogs belonging to the Amerana (Rana boylii) species group from western North America have been particularly severe. Norepinephrine-stimulated skin secretions from the Oregon spotted frog Rana pretiosa Baird and Girard, 1853 were collected from individuals that had been previously infected with the causative agent Batrachochytrium dendrobatidis but had proved resistant to developing chytridiomycosis. These secretions contained a more diverse array of antimicrobial peptides than found in other species from the Amerana group and 14 peptides were isolated in pure form. Determination of their primary structures identified the peptides as esculentin-2PRa and -2PRb; ranatuerin-2PRa, -2PRb, -2PRc, -2PRd, and -2PRe; brevinin-1PRa, -1PRb, -1PRc, and -1PRd; and temporin-PRa, -PRb, and -PRc. The strongly cationic ranatuerin-2PRd and the esculentin-2 peptides, which have not been identified in the secretions of other Amerana species except for the closely related R. luteiventris, showed the highest growth inhibitory potency against microorganisms. The strongly hydrophobic brevinin-1PRd was the most cytotoxic to erythrocytes. Although no clear correlation exists between production of dermal antimicrobial peptides by a species and its resistance to fatal chytridiomycosis, the diversity of these peptides in R. pretiosa may be pivotal in defending the species against environmental pathogens such as B. dendrobatidis.

The Afrotropical Realm includes all of mainland Sub-Saharan Africa and the southern Arabian Peninsula 1 , as well as several large offshore islands: Zanzibar and Pemba; Madagascar; the western Indian Ocean islands of the Seychelles (including Aldabra), Mauritius (including Rodrigues), Réunion, Mayotte, and the Comoros; the Gulf of Guinea islands (Bioko, Príncipe, São Tomé and Pagalu); Socotra; and the Cape Verde Islands. Although Africa finally separated from the rest of the southern land-mass of Gondwanaland some 100 Ma, the African, Arabian and Eurasian plates abutted at least at the end of the Oligocene, and it is only from about 15-10 Ma that Africa has been an isolated land mass (when the African and Arabian land masses rifted apart; see Kingdon 1989; Goudie 2005). The island of Madagascar, on the other hand, separated from the African mainland between 165-140 Ma and has been isolated (as an island) from all other land masses for 87-91 million years (Storey et al. 1995; Torsvik et al. 2000). An extensive process of rifting which began about 30 Ma has left mainland Africa very diverse topographically, with many high mountain ranges, especially on the east of the continent, and with rift valleys that include some of the deepest lakes in the world. Much of Africa is still volcanically active, including Mount Kilimanjaro, its highest peak, soaring some 5,895m above sea-level. A combination of intra-plate hotspots, extensive Cenozoic doming (45 Ma), vulcanism and coastal upwarp has created the world's largest plateau. This is characterized by a "basin and swell" topography unique to the interior of the African continent, and stretching from South Africa to East Africa, with high points including Mount Mulanje (3,002m) in southern Malawi and Mount Rungwe (2,691m) in southern Tanzania (Beentje et al. 1994; Goudie 2005). East and Northeast Africa are bisected by the 6,000-km-long Great Rift (or Gregory Rift), the "passive" margin between the African and East African Plates. This massive feature is visible from space and runs from the Luangwa Valley in Zambia, northeast through Ethiopia, where it meets the Saudi Arabian Plate and continues northwest to the Caucasus Mountains. Not surprisingly, the region is ecologically diverse, with an enormous range of vegetation types from deserts to woodlands and grasslands to rainforests. In West Africa, the agriculturally productive Guinea and Sudanese savannah regions slowly merge into the lowland forests stretching across West Africa. A little further to the east, the highly fragmented, lower Guinea rainforests of Nigeria and western Cameroon open into the vast, lush, relatively intact tropical rainforests of the Congo Basin. Apart from the chain of volcanic mountains centred on western Cameroon and extending into the sea as the Gulf of Guinea islands, West Africa has very few uplands (with the exception of Mount Nimba, and the Loma and other nearby mountains in Sierra Leone, Guinea and Liberia). The eastern edge of the Congo Basin is flanked by the Albertine Rift, a series of high, block-faulted mountain chains that separates the Congo Basin rainforest of Central Africa from the forest/savannah mosaic habitats of East Africa, most famous for their teeming herds of wildebeest and zebra. To the north the Great Rift cuts through the Ethiopian Highlands, home to more than two-thirds of Africa's unique Afro-alpine habitat, while to the southeast of the Great Rift are the Eastern Arc Mountains that continue into the Southern Highlands of Tanzania south to Mount Mulanje in Malawi and the Chimanimani Highlands of Zimbabwe. Patches of forest (now highly fragmented) fringe the coast of much of eastern Africa, from the Juba and Shabelle River Valleys in Somalia south to southeastern South Africa. In the southwestern part of South Africa, the unique Mediterranean fynbos vegetation is dominant, with its remarkable floristic endemism, and further north the Succulent Karoo becomes dominant along the west coast of South Africa. Africa has a low human population density (approximately 30 people per square kilometer in 2005), of which over 60% live in rural areas, but a high population growth rate (over 2.1% per annum, though this is decreasing). Historically, the region has been subject to relatively low levels of anthropogenic disturbance, related not only to low human population densities, but also to widespread poverty (gross income per capita was around US$600 in Sub-Saharan African in 2004). However, 35% of the continent's Gross Domestic Product is concentrated in South Africa, where the human impacts on natural ecosystems and biodiversity have been more severe than in most of the region. Economic growth rates in Africa have been amongst the lowest in the world and still are, though there has been a recent tendency for somewhat faster growth (4.5% in 2004). Although many of Africa's natural habitats are still intact, some parts of the continent have been affected much more than others. Deforestation has been particularly severe in the Upper Guinea forests of West Africa, in the mountains and lowlands of Nigeria and western Cameroon, in many of the mountainous regions of central and East Africa, and in the East African coastal lowlands. This forest loss has been driven largely by expanding subsistence agriculture to support the burgeoning human populations, but also by commercial agriculture and logging. As mentioned above, habitat loss and fragmentation has been particularly severe in South Africa, and above all in the fynbos vegetation of the extreme south and southwest (which has been heavily impacted by invasive species and fire, and well as by general urban and agricultural development). There has also been extensive habitat degradation in the semiarid Sahel region, much of it driven by over-exploitation of resources for basic subsistence by growing human populations. However, in central and south-central Africa, extensive tracts of lowland forest, savannah and grassland remain largely intact. On Madagascar, habitat loss has been especially severe, with almost no natural habitat surviving on the central plateau, and much of the country characterised by very high levels of soil erosion.

This paper reports on contamination levels and their sub-lethal toxicological effects in specimens of the European eel (Anguilla anguilla) in the Orbetello Lagoon, (Tuscany, Italy). Organochlorine pesticides (OC) and polychlorinated biphenyls (PCBs) were investigated as priority pollutants in muscle tissue. Phase I P450 enzymes, i.e., EROD, B(a)PMO and the two reductases (NADH ferryred and cyt c.), and cholinesterase (ChE) were assayed in liver and muscle as sensitive biological indicators of fish health. PCBs, lindane and p,p¢DDE in muscles showed a wide concentration range (0.001-0.025 lg g )1 wet weight) and attained the lowest levels in the eastern basin. High homogeneity and relatively low values were observed for phase I P450 enzymes, suggesting that no significant detoxification process of OC pesticides and PCBs occurred. The threat posed by organophosphate insecticides (OP) and CB compounds was also evidenced by ChE activity. The integrated response of phase I P450 enzymes and ChE activity being an indicator of potential effects of toxic contaminant levels on reproductive success and population decline of eels, can be used to assess the overall lagoon quality. Hydrobiologia (2005) 550:237-249 Ó Springer 2005 P. Viaroli, M. Mistri, M.

Most of the available data on declining populations of amphibians pertain to frogs and, to a lesser extent, salamanders. In keeping with their generally less understood biology, the population trends and conservation status of caecilian amphibians (Gymnophiona) are also much less known. We reviewed reports of threats to and declines of populations of caecilians. Despite a lack of field-study details (e.g., localities, dates, and sampling methods) and quantitative data, there are several recent reports of threats to and declines and extinctions of caecilians. A range of causal explanations (habitat loss, pollution, chytridiomycosis, and scientific collecting) for these perceived declines have been proposed but little or no associated evidence has been given. Although caecilians are often considered rare and thought to require pristine habitat, published, quantitative data demonstrate that at least some species can occur in high abundance in disturbed, synanthropic environments. Few estimates of caecilian population parameters have been made and very few field methods have been tested, so the assumed rarity of any taxa remains inadequately demonstrated. Distribution and taxonomic data are also inadequate. Because they are generally poorly known and often cryptic, caecilians can be overlooked in standard faunal surveys, meaning that lack of opportunistic collection over several years might not represent evidence of decline. The conservation status of most species must be considered data deficient. More precise assessments will require a substantial increase in all areas of caecilian research, especially those involving new fieldwork. Future reports of caecilian conservation biology need to be explicit and more quantitative.

Recruitment is essential for the maintenance of populations, but far more is typically known about the more easily-observed adult stages than their smaller, often microscopic early life-history counterparts. This discrepancy can be particularly problematic for populations of foundation species that create biogenic habitat for a multitude of other taxa, but are themselves prime candidates for exploitation, fragmentation, and loss, and therefore become the focus of restoration eVorts partly or fully dependent on recruitment. The purpose of this study was to improve ecological understanding for early life-history stages of the habitat-forming marine alga Cystoseira barbata (Stackhouse) C. Agardh (Fucales: Sargassaceae), member of a genus that has experienced considerable fragmentation and population decline on European coasts. Using experimental manipulations of water temperature, light intensity, and sediment accumulation, we observed that sediment virtually precluded recruitment of C. barbata, and greatly impacted the survival of recently settled germlings (up to »83% mortality). Stronger intensities of light facilitated the growth of germlings, including the capacity for »50% of them to outgrow detrimental sediment and survive. Temperature (10 vs. 16°C) had no eVect on early recruitment, survival, or growth. This information helps to identify likely causes and locations of recruitment failure, and by extension, the conditions needed (either naturally or through human intervention) to facilitate recruitment and possible habitat restoration. Ultimately, this knowledge can increase our capacity to predict population persistence and the likely success of restoration eVorts.

In this paper we present a population declining ant colony optimization (PDACO) multiuser detector for asynchronous CDMA communications. Ant colony optimization (ACO) algorithms have already been used in multiuser detection in CDMA systems; however, as the pheromone accumulates, we may not get a global optimum because it stops searching early. PDACO can enlarge searching range through increasing the initial population of the ant colony, and the population declines in successive iterations. So, the performance of PDACO is superior with the same computational complexity. PDACO is applied to multiuser detection in asynchronous CDMA systems over slowly multipath Rayleigh-fading channels in this paper. Via computer simulations it is shown that the performance of PDACO detector is much better in bit-error rate and near-far effect resistance than conventional detector, ACO detector and genetic algorithm detector, and is close the optimal multiuser detector.

The Greater sage-grouse (Centrocercus urophasianus) occupies the sage brush habitats of Western North America. Large population declines in the last several decades have made it a candidate for possible listing under the Endangered Species Act. Listing was recently avoided in part because local working groups are developing long-range management plans in conjunction with federal and local agencies. The Foster Creek Conservation District, a working group in Douglas County, Washington, saw the potential for system dynamics to synthesize known sage-grouse dynamics and local land use patterns to support development of their Habitat Conservation Plan and subsequent land management decisions. This case study highlights the integration of science, local knowledge and social concerns into a participatory process that uses system dynamics as a forum for the exploration of the impacts of land management decisions upon the sage-grouse population and the landowners of Douglas County, Washington.

The European ground squirrel (Spermophilus citellus) is an endangered species and typically inhabits steppes and open woodland of Central Europe and the Balkans. Knowledge about its distribution and status in the southern part of its range is scanty. Distribution of the species in Bulgaria over two periods (1950-1989 and 1990-2008) and recent status of 90 colonies in three model regions (mountain region, Sofia field and Thracian valley) are evaluated in the paper. Data on 254 UTM squares inhabited by S. citellus during the first period and 212 UTM squares inhabited during the second period were available, but these data could not be compared because of the different survey methods used. S. citellus colonies in southwestern Bulgaria may be already extinct and population decline is supposed to take place at the southwestern periphery of the species' distribution range. About 30% out of 90 investigated colonies have disappeared, 28% are vulnerable and only 42% are stable. The biggest part of the extinct colonies was found in the Sofia field and Mountain region. Pastures are the most frequently occupied land use type (72%) in Bulgaria and major threats for the S. citellus population include pasture degradation, building up, intensification of agriculture, interruption of biological corridors and flooding. The S. citellus population in Bulgaria has been probably declining and current status of the species is unfavourable. The S. citellus conservation status in Bulgaria should be enhanced and the species should be included in the new Red Book of Animals in Bulgaria in the category "vulnerable" and should be protected according to the national biodiversity legislation.

In Romania, the phenomenon of demographic transition has been present since the second half of the last century, having certain features also met in the developed countries: the drop in fertility, the increase in life expectancy, the decrease in infant mortality. After 1990, the phenomenon of demographic transition has been emphasized by the effects of society’s transition from the communist

Hudson's Bay Company records were used to estimate the 1786-1911 annual number of moose (Alces alces andersonfi) and caribou (Rangifer tarandus caribou) involved in trade by northern Ojibwa natives to the company post at Osnaburgh House (51~ 90~ in northwest Ontario, Canada. The human population for the early 19th century, and the number and severity of human starvations from 1786 to 1911 were estimated. The extent Environmental Management Vol. 17, No. 4, pp. 477-489 9 1993 Springer-Verlag New York Inc. 478 R. Fritz and others 2 0~'~-"2 0 Pickle L. La# Seu.t ~ 9 . . House ~ " OJd OsnabuJ"~h La 9 ~,eel / ] House i. iili ii! : 6" Lookout. (E~-V~"-"t~'~J~~ 94 = 90 "= 86 = 82 = 78 =

As urbanized areas expand and develop throughout the world, the importance of understanding their effects on wildlife increases. Living in cities may be stressful for animals but may also provide benefits at the same time, and the sum of these effects should manifest in the body condition of individuals. Studies addressing this phenomenon tend to evaluate one or few indices of body condition, each of which may be subject to various confounding effects and seasonal changes. In this study we used multiple approaches to assess the effects of urbanization on adult body condition in house sparrows (Passer domesticus), a passerine undergoing population declines in urban habitats. In line with earlier studies, we found that sparrows in more urbanized habitats have reduced body mass. However, birds had similar scaled mass index (body mass corrected for body size) along the urbanization gradient at all times of the year, contradicting the previous result on type-1 regression residuals. In the non-breeding season, urban and rural birds had similar levels of corticosterone, hematocrit, and heterophil:lymphocyte ratio. In the molting season, hematocrit indicated better condition in rural birds whereas H:L ratio showed the opposite; however, these trends were not consistent between age groups. Two condition-dependent plumage traits, male bib size and wing bar size, showed no systematic variation along the gradient of urbanization. These results suggest that the environmental conditions experienced by adult house sparrows are not more stressful in more urbanized habitats, and they also highlight the importance of considering multiple indices of body condition.

Gibbons are among the best-studied Asian primates, but few studies address their demography and life history strategies. We used annual censuses to study the demography of agile gibbons (Hylobates agilis) between 1998 and 2009 in rain forests of Bukit Barisan Selatan National Park, Indonesia. The population declined from 22 individuals (9 groups) to 14 individuals (5 groups) over the 12 yr of study. Infant survival to the juvenile age class was 33.3%, and 16.7% of infants survived to the subadult age class. The interbirth interval was 3.83±1.15 yr and birth rate was 0.22-0.28 infants female -1 yr -1 . Two groups colonized the study area but subsequently disappeared. We documented 7 immigrations, 17 disappearances, and ≥10 transients in the population. Compared to lar gibbons (Hylobates lar) and Bornean white-bearded gibbons (Hylobates albibarbis), Way Canguk's agile gibbon population is characterized by slow reproduction, low survival, and high group turnover. We hypothesize that, although the habitat is high in fruit resources, agile gibbons may be displaced or excluded from the best fruit resources by larger and more numerous competitors, incurring costs of decreased opportunities to forage and increased travel, and leading to higher mortality for young agile gibbons. The reproductive potential of this agile gibbon population is insufficient to compensate for high mortality, and the population is unlikely to persist without immigration from outside the area. Given the agile gibbons' endangered status and limited capacity to respond demographically to change, it is likely that intensive management interventions will be required to conserve this species.

No reliable estimates exist for populations of Andean bears (Tremarctos omatus). They occupy >260,000 km2 in 5 Andean countries, and if their densities are comparable to those of North American black bears (Ursus americanus), the total population may be >20,000. Unbroken tracts of the Andes stretching more than 200 km and extending over 3000 m of elevation exist for this

Coastal prairies are the primary winter destination for two dozen species of migratory grassland birds and losses of this habitat have proven detrimental to their populations. As a result, some of Partners in Flight's (PIF) highest priority birds are grassland species. To examine grassland bird use of coastal prairies, Project Prairie Birds survey methodology was designed and field work was initiated in 1998. Avian surveys were conducted at 34 sites, each with multiple tran- sects for a minimum of two years by all-volunteer, three-person crews identifying all species flushed from vegetation. Seasonal vegetation surveys measured five variables using five one square-meter sample areas. We also measured vertical thickness using a density board. We selected nine sites (26.5%) with three or more years of survey data for analysis. Thirty-nine species were detected of which 36% have PIF combined species assessment scores of 10 or above. In addition, 24% of the individuals were Le Conte...

Although some sea turtle populations are showing encouraging signs of recovery, others continue to decline. Reversing population declines requires an understanding of the primary factor(s) that underlie this persistent demographic trend. The list of putative factors includes direct turtle and egg harvest, egg predation, loss or degradation of nesting beach habitat, fisheries bycatch, pollution, and large-scale changes in oceanographic conditions and nutrient availability. Recently, fisheries bycatch, in particular bycatch from longline fisheries, has received increased attention and has been proposed as a primary source of turtle mortality. We reviewed the existing data on the relative impact of longline bycatch on sea turtle populations. Although bycatch rates from individual longline vessels are extremely low, the amount of gear deployed by longline vessels suggests that cumulative bycatch of turtles from older age classes is substantial. Current estimates suggest that even if pelagic longlines are not the largest single source of fisheries-related mortality, longline bycatch is high enough to warrant management actions in all fleets that encounter sea turtles. Nevertheless, preliminary data also suggest that bycatch from gillnets and trawl fisheries is equally high or higher than longline bycatch with far higher mortality rates. Until gillnet and trawl fisheries are subject to the same level of scrutiny given to pelagic longlines, our understanding of the overall impact of fisheries bycatch on vulnerable sea turtle populations will be incomplete.

Amphibian populations have declined and disappeared in protected and apparently undisturbed areas around the world, especially in montane areas of the tropics. The amphibian chytrid fungus, Batrachochytrium dendrobatidis has been implicated in many of these declines. In Costa Rica most declines occurred in the highlands. We examined an amphibian collection made in Braulio Carrillo National Park in 1986 for the amphibian chytrid fungus B. dendrobatidis, prior to the well documented amphibian declines in Monteverde, along an altitudinal transect from 100 to 2600 m elev. Skin from the pelvic patch of 202 specimens corresponding to 30 species was examined histologically to determine whether the disease was present in the highlands of the park before amphibian populations declined. For comparison, in 2002 we collected and examined 18 specimens of seven species of Eleutherodactylus and Craugastor from two other lowland Caribbean sites. The chytrid fungus was present in almost all altitudes in 1986, including lower areas. The pathogen was also found in both species that later declined and in species that did not do so. We detected chytrid fungus on amphibians collected at almost all altitudes in 1986, including those sampled at 280 m. B. dendrobatidis was abundant in frogs collected in the 2002 survey, and seems to be endemic in most of Costa Rica. More retrospective museum surveys are needed in order to determine whether it can be found in the area before 1986.

Recent archaeological data assess that Tahiti and the Marquesas Islands were densely populated at contact with Europeans and then experienced a tremendous decline. This phenomenon is most often attributed to epidemics, but steady negative increase is rarely mentioned. This paper shows that the population of Tahiti could have reached 180,000 at contact, based on a retrodiction from the 1881 census using data on epidemic mortality and yearly decline rates observed in the second half of the nineteenth century, and provides estimates of the impact of both types of mortality. When data are lacking, mostly before 1848 in Tahiti and 1886 in the Marquesas, we rely on missionaries', administrators', and doctors' reports. Due to no exposure to childhood and other diseases common on continents, Polynesians had low immunity as shown by age-specific death rates until the 1918 flu and the 1951 measles epidemics. Two or three decades after contact, STDs, tuberculosis and other introduced infectious diseases resulted in steady population decline due to reduced birth rates and very high death rates. Health services were available for Europeans soon after the takeover, but much later and discontinuously for natives. Constant negative increase extended far into the colonial period, including after efficient drugs were discovered in the 1880s, and became the main contributor to overall demographic decline in the Marquesas Islands, where health services were lacking most of the time before 1924, mostly in the Southeastern group.

1. Water hyacinth (Eichhornia crassipes) is one of the world's most invasive aquatic plants and is known to cause significant ecological and socio-economic effects. 2. Water hyacinth can alter water clarity and decrease phytoplankton production, dissolved oxygen, nitrogen, phosphorous, heavy metals and concentrations of other contaminants. 3. The effects of water hyacinth on ecological communities appear to be largely nonlinear. Abundance and diversity of aquatic invertebrates generally increase in response to increased habitat heterogeneity and structural complexity provided by water hyacinth but decrease due to decreased phytoplankton (food) availability. 4. Effects of water hyacinth on fish are largely dependent on original community composition and food-web structure. A more diverse and abundant epiphytic invertebrate community may increase fish abundance and diversity, but a decrease in phytoplankton may decrease dissolved oxygen concentrations and planktivorous fish abundance, subsequently affecting higher trophic levels. 5. Little is known about the effects of water hyacinth on waterbird communities; however, increases in macroinvertebrate and fish abundance and diversity suggest a potentially positive interaction with waterbirds when water hyacinth is at moderate density. 6. The socio-economic effects of water hyacinth are dependent on the extent of the invasion, the uses of the impacted waterbody, control methods and the response to control efforts. Ecosystem-level research programmes that simultaneously monitor the effects of water hyacinth on multiple trophic-levels are needed to further our understanding of invasive species.

The alarming rate of deforestation in Madagascar is driving some endemic primates to extinction. Surprisingly, anthropogenic habitat disturbance is not always deleterious. The effect of disturbance on lemur abundance may be related to diet, with frugivorous species more prone to population declines than folivores or insectivores. To test the effects of disturbance on lemur abundance and group size, we surveyed 2 sites within contiguous forest at Ranomafana National Park, 1 lightly disturbed primary forest (Vato) and 1 heavily logged forest (Tala). We quantified forest structure variables along 6 survey routes and conducted 68 diurnal and 42 nocturnal lemur surveys. Canopy closure, canopy height, and understory visibility were greater in Vato than in Tala. We encountered 2 frugivorous lemurs (Eulemur rufifrons, Varecia variegata) and 1 folivore (Avahi peyrierasi) significantly more frequently in Vato than in Tala, whereas the opposite was true for the insectivorous Microcebus rufus. Rates did not differ statistically for 1 frugivore (Eulemur rubriventer) and 2 folivores (Propithecus edwardsi, Hapalemur griseus). Comparisons across the 6 survey routes suggest that the abundance was heterogeneous within as well as between sites. Neither group size nor composition differed between sites. Encounter rates for Varecia variegata were positively related to canopy closure, and encounter rates for Avahi peyrierasi were positively related to canopy height. Encounter rates for Microcebus rufus were negatively related to canopy closure, height, and understory visibility. Similar to other studies, the results suggest that some lemurs, including folivores, may cope with anthropogenic disturbance better than others, including some frugivores. Lemur abundance is heterogeneous, though, even on small spatial scales.

The yellow stem borer, Scirpqhugu incertulas (Walker), emerged as the dominant pest of deepwater rice in an intensive 4-year ecological study in two farmers' fields in central Bangladesh. There were six annual broods. In brood 1 developing in transplanted dry season rice and brood 2 migrating to preflooded deepwater rice, the population density and level of stem damage were low. Borer populations built up in broods 3, 4 and 5 in flooded deepwater rice to reach densities of 16-52 immatures m-', which damaged 33-80% of the stems. Borer populations declined in brood 6 at the end of the deepwater rice season, the larvae entering diapause in the field stubbles. The major factors regulating the populations were as follows: the incidence of weather extremes (temperatures >34"C with relative humidity <70%) before flooding which are lethal to eggs and first instars; the presence of succulent, elongating stems which are. favourable for larval penetration and development; the occurrence of rapid water rises (68 cm day-') which drown the immature stages; the activity of natural enemies, particularly the complex of egg parasitoids, and spider and orthopteran predators; and the harvesting and threshing operations which kill many diapausing larvae in the stems. An early season population outbreak in 1977 was associated with exceptionally mild, wet weather; the highest population density and level of stem damage followed a late surge of flooding in 1980 that produced a second flush in elongating stems. The ecological studies revealed two occasions during the season when control measures might be feasible.

Japan’s population is ranked 10th largest in the world, yet the country is experiencing a great demographic shift, with current fertility rates registering at an alarming decline.
Rural spaces are particularly affected by the depopulating trend, as in recent decades
large numbers have relocated to urban areas. This rural exodus gives rise to a series of social and environmental issues which will be analysed throughout this dissertation.
I will introduce two interviews focused on community building initiatives in Okayama and Shiga prefectures. These interviews will help demonstrate the overall aim of my thesis: that non-governmental community-building projects are effective in driving revitalization in these rural areas, by adding social and economic value. These projects can be seen as a beneficial compliment to the pre-existing governmental approach.

Invasive alien species constitute a major threat to biodiversity and cases of extinction caused by invasive alien animals are abundant. However, while invasive alien plants also harm native biota there exists a lack of cases demonstrating their ability to cause extinction of native plant species. Different alien species (vertebrates, invertebrates, pathogens etc.) commonly deliver different simultaneous impacts like predation, disease or competition. In such situations, assessing the contribution of plant invasion in causing decline of a given plant population in its natural habitat can be difficult, yet is desirable to avoid or minimize wastage of managers' resources. Using native angiosperms in lowland wet forests of Mauritius, we first compared native seedling diversity in forest areas that have been weeded of invasive alien plants about a decade previously, with adjacent similar but non-weeded areas. Then, using the weeded area, we compared results of native plant surveys carried out around the time that invasive alien plants were controlled, with the same community about a decade latter. Species richness and abundance of seedlings were higher in the weeded areas compared to the adjacent non weeded forest. We also found that several species that were presumed extinct or critically threatened with extinction had recovered dramatically as a consequence of the sole removal of invasive alien plants. This shows that the threat posed by invasive alien plants can be overwhelmingly important in driving native plant population declines in tropical forests and that imminent plant extinctions can be averted by timely control of alien plants.

Marine biodiversity worldwide is under increasing threat, primarily as a result of over-harvesting, pollution and climate change. Chondrichthyan fishes (sharks, rays and chimaeras) have a perceived higher intrinsic risk of extinction compared to other fish. Direct fishing mortality has driven many declines, even though some smaller fisheries persist without associated declines. Mixedspecies fisheries are of particular concern, as is illegal, unreported and unregulated (IUU) fishing. The lack of specific management and reporting mechanisms for the latter means that many chondrichthyans might already be susceptible to extinction from stochastic processes entirely unrelated to fishing pressure itself. Chondrichthyans might also suffer relatively more than other marine taxa from the effects of fishing and habitat loss and degradation given coastal habitat use for specific life stages. The effects of invasive species and pollution are as yet too poorly understood to predict their long-term role in affecting chondrichthyan population sizes. The spatial distribution of threatened chondrichthyan species under World Conservation Union (IUCN) Red List criteria are clustered mainly in (1) south-eastern South America;

Biodiversity loss can precipitate extinction cascades and impair ecological processes. These 'downstream' effects will be exacerbated if functionally important taxa are tightly linked with species threatened by extinction or population decline. We review the current evidence that such a scenario is currently playing out in the linked declines of persistently hunted mammal populations and the dung beetles communities (Coleoptera: Scarabaeidae: Scarabaeinae) that depend on them for adult and larval food resources. Through a close evolutionary association, mammal assemblages have played a fundamental role in structuring extant dung beetle communities. Today many game mammal species' populations are severely depleted by subsistence or commercial hunting, especially in tropical forest systems. Multiple lines of evidence from temperate and tropical systems indicate that the regional-scale decline or extirpation of medium and large bodied mammal faunas can severely disrupt the diversity and abundance of dung beetle communities through alterations in the composition and availability of dung resources. These observed community disassemblies have significant short-and long-term implications for the maintenance of key ecosystem processes including nutrient recycling and secondary seed dispersal. Identifying the species-and community-level traits that buffer or exacerbate these species and functional responses is essential if we are to develop a better understanding of the cascading ecological consequences of hunting in tropical forests.

Long-term records of nesting numbers, or proxies to nesting numbers, show a precipitous decline in the size of many sea turtle populations. Population declines are most frequently attributed to fisheries bycatch, although direct quantification of this level of mortality is rare. We used satellite-tracking records for turtles in the Mediterranean Sea and Pacific, Atlantic and Indian Oceans to identify when turtles had been captured. Evidence for capture came from a combination of an increase in good quality locations from transmitters, transmitters moving inland to coastal towns and villages, and on-board submergence data, showing that transmitters had come out of the water. A high level of mortality was calculated, confirming current concerns regarding the outlook for sea turtles.

Numerous studies have documented the decline of amphibians following timber harvest. However, direct evidence concerning the mechanisms of population decline is lacking and hinders attempts to develop conservation or recovery plans and solutions for forest species. We summarized the mechanisms by which abundance of amphibians may initially decline following timber harvest into three testable hypotheses: (1) mortality, (2) retreat, and (3) evacuation. Here, we tested the evacuation hypothesis within a large-scale, replicated experiment. We used drift fences with pitfall traps to capture pond-breeding amphibians moving out of experimental clearcut quadrants and into control quadrants at four replicate arrays located within the Daniel Boone Conservation Area on the upper Ozark Plateau in Warren County, Missouri, USA. During the preharvest year of 2004, only 51.6% of the 312 individuals captured were moving out of pre-clearcut quadrants, and movement did not differ from random. In contrast, during both postharvest years of 2005 and 2006, the number of captures along the quadrant edge increased, and a higher proportion of individuals (59.9% and 56.6%, respectively, by year) were moving out of clearcut quadrants than entering. Salamanders moved out of clearcuts in large percentages (Ambystoma annulatum, 78.2% in 2005(Ambystoma annulatum, 78.2% in , 78.2% in 2006 A. maculatum, 64.0% in 2005, 57.1% in 2006. Frogs and toads also moved out of clearcut quadrants, but in lower percentages (Bufo americanus, 59.6% in 2005(Bufo americanus, 59.6% in , 53.3% in 2006 Rana clamitans, 52.7% in 2006). Salamanders moved out of clearcuts with low-wood treatments more than out of clearcuts with high-wood treatments. Movement of salamanders out of clearcuts was independent of sex. Estimated movement out of clearcuts represented between 8.7% and 35.0% of the total breeding adults captured for two species of salamanders. Although we recognize that some portion of the amphibian population may retreat underground for short periods and others may not survive the effects of timber harvest, these data are the first direct evidence showing that individuals are capable of leaving clearcuts and shifting habitat use.

The population of the Spartiates declined from some 8,000 to fewer than 1,000 in the Classical and Hellenistic eras. The causes and consequences of this decline are impor- tant for an understanding not only of ancient Greek history, but also of the study of pre-industrial populations and population dynamics more generally. This work sur- veys a range of representative modern scholarship on this phenomenon and discusses topics such as family planning, elite under-reproduction, wealth polarization, and no- tions of eugenic exclusivity, and suggests avenues for further research.

During June and July of 2009, sudden deaths, tremulous movements and population declines of adult honey bees were reported by the beekeepers in the region of Peloponnesus (Mt. Mainalo), Greece. A preliminary study was carried out to investigate these unexplained phenomena in this region. In total, 37 bee samples, two brood frames containing honey bee brood of various ages, eight sugar samples and four sugar patties were collected from the affected colonies. The samples were tested for a range of pests, pathogens and pesticides. Symptomatic adult honey bees tested positive for Varroa destructor, Nosema ceranae, Chronic bee paralysis virus (CBPV), Acute paralysis virus (ABPV), Deformed wing virus (DWV), Sacbrood virus (SBV) and Black queen cell virus (BQCV), but negative for Acarapis woodi. American Foulbrood was absent from the brood samples. Chemical analysis revealed that amitraz, thiametoxan, clothianidin and acetamiprid were all absent from symptomatic adult bees, sugar and sugar patty samples. However, some bee samples, were contaminated with imidacloprid in concentrations between 14 ng/g and 39 ng/g tissue. We present: the infection of Greek honey bees by multiple viruses; the presence of N. ceranae in Greek honey bees and the first record of imidacloprid (neonicotonoid) residues in Greek honey bee tissues. The presence of multiple pathogens and pesticides made it difficult to associate a single specific cause to the depopulation phenomena observed in Greece, although we believe that viruses and N. ceranae synergistically played the most important role. A follow up in-depth survey across all Greek regions is required to provide context to these preliminary findings.

本文被《中国社会科学文摘》2019年第3期转载
Archaeology can generate significant knowledge of the past independently. This article analyzes archaeological evidence dating to the time of the Xia dynasty (a.k.a. the late Longshan era and the Erlitou era) . It reveals a series of momentous events in the age of the Xia dynasty, all of which are not recorded in written documents. This research shows that archaeological evidenc can shed important new light on the past and textual records.
Key words： Archaeological evidence, 1900 BC, Catastrophe, Collapse, Social reconfiguration